MassEmail Queued Items quit working

[qpoint]

Had Campaign and MassEmails working fine for a while. But it has stopped working. The "Queued Items" list is now always empty. Viewing the TargetList shows all the Contacts correctly.

To investigate, I then created a new Campaign with 1 simple test TargetList and then added a MassEmail with the same TargetList (which used to work), now no longer works...the Queued Items list is always empty.

Direct api call in browser confirms empty queue: ..../api/v1/MassEmail/652055654c6789a15/queueItems
Shows {"total":0,"list":[]}

Viewing of the TargetList is ok and shows the Contacts: ..../api/v1/TargetList/65205e723c7a17d00

There is now no way to create any MassEmail, as the queue is always empty. I've tried many different tests.

This problem started when I wanted to understand the behavior when adding a second TargetList to a Campaign, and just specifying the one TargetList on a MassEmail.

I think something got corrupted, as even going back to the simplest campaign tests no longer work.

Appreciate any advice on how to resolve or troubleshoot.

[qpoint]

Figured it out, several factors threw me off. I mistakenly thought the Queue Items are populated immediately.
Got this impression from earlier tests which were via api, and with MassEmail Date Start treated as Utc (unlike in the UI, which is local tz), 7 time zones later for me.

In viewing the code, it is not considered for queueing until the MassEmail Date Start is past.
Actual population of the queue occurs when the Send Mass Emails cron runs, which is set to the default of 15 minutes after the hour. Once the MassEmail Date Start was brought forward so it could trigger, the Queue Items were populated.